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Imidazole-Based Monomer as Functional Unit for the Specific Detection of Paraxanthine in Aqueous Environments. CHEMOSENSORS 2022. [DOI: 10.3390/chemosensors10080301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
In the context of personalized medicine, the paraxanthine-to-caffeine ratio is an accepted standard for the optimization of the dose-response effect of many pharmaceuticals in individual patients. There is a strong drive towards the development of cheaper and portable devices for the detection of biomarkers, including paraxanthine and caffeine, which requires materials with high binding efficiency and specificity. We designed a recognition unit specific for paraxanthine which can discriminate molecules with small structural differences and can be used to increase the sensitivity of sensors. A number of functional units were screened by nuclear magnetic resonance for their ability to form specific binding interactions with paraxanthine in water and negligible interactions with its structural analogue caffeine. Imidazole was identified as the unit showing the most promising results and its two polymerizable derivatives were evaluated by isothermal titration calorimetry to identify the best monomer. The data suggested that 4-vinylimidazole was the most promising unit forming specific and strong binding interaction with paraxanthine. The calorimetry experiments allowed also the determination of the thermodynamic parameters of all interactions and the association constant values. Optimization of polymerization protocols in water, achieving high monomer conversions and chemical yields, demonstrate the suitability of the selected functional monomer for polymer preparations, targeting the detection of paraxanthine in aqueous environments.
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Hofstetter RK, Schulig L, Bethmann J, Grimm M, Sager M, Aude P, Keßler R, Kim S, Weitschies W, Link A. Supercritical fluid extraction-supercritical fluid chromatography of saliva: Single-quadrupole mass spectrometry monitoring of caffeine for gastric emptying studies †. J Sep Sci 2021; 44:3700-3716. [PMID: 34355502 DOI: 10.1002/jssc.202100443] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 08/02/2021] [Accepted: 08/02/2021] [Indexed: 11/06/2022]
Abstract
Saliva is an attractive sampling matrix for measuring various endogenous and exogeneous substances but requires sample treatment prior to chromatographic analysis. Exploiting supercritical CO2 for both extraction and chromatography simplifies sample preparation, reduces organic solvent consumption, and minimizes exposure to potentially infectious samples, but has not yet been applied to oral fluid. Here, we demonstrate the feasibility and benefits of online supercritical fluid extraction coupled to supercritical fluid chromatography and single-quadrupole mass spectrometry for monitoring the model salivary tracer caffeine. A comparison of 13 C- and 32 S-labeled internal standards with external standard calibration confirmed the superiority of stable isotope-labeled caffeine over nonanalogous internal standards. As proof of concept, the validated method was applied to saliva from a magnetic resonance imaging study of gastric emptying. After administration of 35 mg caffeine via ice capsule, salivary levels correlated with magnetic resonance imaging data, corroborating caffeine's usefulness as tracer of gastric emptying (R2 = 0.945). In contrast to off-line methods, online quantification required only minute amounts of organic solvents and a single manual operation prior to online bioanalysis of saliva, thus demonstrating the usefulness of CO2 -based extraction and separation techniques for potentially infective biomatrices.
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Affiliation(s)
- Robert K Hofstetter
- Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, University of Greifswald, Greifswald, Germany
| | - Lukas Schulig
- Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, University of Greifswald, Greifswald, Germany
| | - Jonas Bethmann
- Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, University of Greifswald, Greifswald, Germany
| | - Michael Grimm
- Department of Biopharmaceutics and Pharmaceutical Technology, Institute of Pharmacy, University of Greifswald, Greifswald, Germany
| | - Maximilian Sager
- Department of Biopharmaceutics and Pharmaceutical Technology, Institute of Pharmacy, University of Greifswald, Greifswald, Germany
| | - Philipp Aude
- Department of Biopharmaceutics and Pharmaceutical Technology, Institute of Pharmacy, University of Greifswald, Greifswald, Germany
| | - Rebecca Keßler
- Department of Diagnostic Radiology and Neuroradiology, University Hospital Greifswald, Greifswald, Germany
| | - Simon Kim
- Department of Trauma, Reconstructive Surgery and Rehabilitation Medicine, University Medicine Greifswald, Greifswald, Germany.,Leibniz Institute for Plasma Science and Technology (INP Greifswald), Greifswald, Germany
| | - Werner Weitschies
- Department of Biopharmaceutics and Pharmaceutical Technology, Institute of Pharmacy, University of Greifswald, Greifswald, Germany
| | - Andreas Link
- Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, University of Greifswald, Greifswald, Germany
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Anastasiadi RM, Berti F, Colomban S, Tavagnacco C, Navarini L, Resmini M. Simultaneous Quantification of Antioxidants Paraxanthine and Caffeine in Human Saliva by Electrochemical Sensing for CYP1A2 Phenotyping. Antioxidants (Basel) 2020; 10:antiox10010010. [PMID: 33374269 PMCID: PMC7823619 DOI: 10.3390/antiox10010010] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 12/15/2020] [Accepted: 12/21/2020] [Indexed: 11/16/2022] Open
Abstract
The enzyme CYP1A2 is responsible for the metabolism of numerous antioxidants in the body, including caffeine, which is transformed into paraxanthine, its main primary metabolite. Both molecules are known for their antioxidant and pro-oxidant characteristics, and the paraxanthine-to-caffeine molar ratio is a widely accepted metric for CYP1A2 phenotyping, to optimize dose–response effects in individual patients. We developed a simple, cheap and fast electrochemical based method for the simultaneous quantification of paraxanthine and caffeine in human saliva, by differential pulse voltammetry, using an anodically pretreated glassy carbon electrode. Cyclic voltammetry experiments revealed for the first time that the oxidation of paraxanthine is diffusion controlled with an irreversible peak at ca. +1.24 V (vs. Ag/AgCl) in a 0.1 M H2SO4 solution, and that the mechanism occurs via the transfer of two electrons and two protons. The simultaneous quantification of paraxanthine and caffeine was demonstrated in 0.1 M H2SO4 and spiked human saliva samples. In the latter case, limits of detection of 2.89 μM for paraxanthine and 5.80 μM for caffeine were obtained, respectively. The sensor is reliable, providing a relative standard deviation within 7% (n = 6). Potential applicability of the sensing platform was demonstrated by running a small scale trial on five healthy volunteers, with simultaneous quantification by differential pulse voltammetry (DPV) of paraxanthine and caffeine in saliva samples collected at 1, 3 and 6 h postdose administration. The results were validated by ultra-high pressure liquid chromatography and shown to have a high correlation factor (r = 0.994).
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Affiliation(s)
- Rozalia-Maria Anastasiadi
- Department of Chemistry, Queen Mary University of London, Mile End Road, London E1 4NS, UK
- Correspondence: (R.-M.A.); (M.R.)
| | - Federico Berti
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, via L. Giorgieri 1, 34127 Trieste, Italy; (F.B.); (C.T.)
| | - Silvia Colomban
- Aromalab, illycaffè S.p.A., Area Science Park, Localita’ Padriciano 99, 34149 Trieste, Italy; (S.C.); (L.N.)
| | - Claudio Tavagnacco
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, via L. Giorgieri 1, 34127 Trieste, Italy; (F.B.); (C.T.)
| | - Luciano Navarini
- Aromalab, illycaffè S.p.A., Area Science Park, Localita’ Padriciano 99, 34149 Trieste, Italy; (S.C.); (L.N.)
| | - Marina Resmini
- Department of Chemistry, Queen Mary University of London, Mile End Road, London E1 4NS, UK
- Correspondence: (R.-M.A.); (M.R.)
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Manig F, Hellwig M, Pietz F, Henle T. Quantitation of free glycation compounds in saliva. PLoS One 2019; 14:e0220208. [PMID: 31532774 PMCID: PMC6750567 DOI: 10.1371/journal.pone.0220208] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 07/10/2019] [Indexed: 12/14/2022] Open
Abstract
In the course of the Maillard reaction, which occurs during heating of food but also under physiological condition, a broad spectrum of reaction products is formed. Among them, the advanced glycation endproducts (AGEs) Nε-carboxymethyllysine (CML), pyrraline (Pyr), methylglyoxal-derived hydroimidazolone 1 (MG-H1) and Nε-carboxyethyllysine (CEL) are the quantitatively dominating compounds during later reaction stages. Those dietary glycation compounds are under discussion as to be associated with chronic inflammation and the pathophysiological consequences of diseases such as diabetes. In the present study, the concentration of individual glycation compounds in saliva was monitored for the first time and related to their dietary uptake. Fasting saliva of 33 metabolically healthy subjects was analyzed with HPLC-MS/MS. The observed levels of individual glycation compounds ranged from 0.5 to 55.2 ng/ml and differed both intra- and interindividually. Patterns did not correlate with subject-related features such as vegetarianism or sports activities, indicating that dietary intake may play an important role. Therefore, six volunteers were asked to eat a raw food diet free of glycation compounds for two days. Within two days, salivary Pyr was lowered from median 1.7 ng/ml to a minimum level below the limit of detection, and MG-H1 decreased from 3.6 to 1.7 ng/ml in in a time-dependent manner after two days. Salivary CML and CEL concentrations were not affected. Therefore, measuring Pyr and MG-H1 in saliva is a suitable diagnostic tool to monitor the dietary intake and metabolic transit of glycation compounds present in heated foods.
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Affiliation(s)
- Friederike Manig
- Chair of Food Chemistry, Technische Universität Dresden, Dresden, Germany
- * E-mail: (TH); (MH); (FM)
| | - Michael Hellwig
- Chair of Food Chemistry, Technische Universität Dresden, Dresden, Germany
- * E-mail: (TH); (MH); (FM)
| | - Franziska Pietz
- Chair of Food Chemistry, Technische Universität Dresden, Dresden, Germany
| | - Thomas Henle
- Chair of Food Chemistry, Technische Universität Dresden, Dresden, Germany
- * E-mail: (TH); (MH); (FM)
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Redivo L, Anastasiadi RM, Pividori M, Berti F, Peressi M, Di Tommaso D, Resmini M. Prediction of self-assembly of adenosine analogues in solution: a computational approach validated by isothermal titration calorimetry. Phys Chem Chem Phys 2019; 21:4258-4267. [PMID: 30644470 DOI: 10.1039/c8cp05647a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The recent discovery of the role of adenosine-analogues as neuroprotectants and cognitive enhancers has sparked interest in these molecules as new therapeutic drugs. Understanding the behavior of these molecules in solution and predicting their ability to self-assemble will accelerate new discoveries. We propose a computational approach based on density functional theory, a polarizable continuum solvation description of the aqueous environment, and an efficient search procedure to probe the potential energy surface, to determine the structure and thermodynamic stability of molecular clusters of adenosine analogues in solution, using caffeine as a model. The method was validated as a tool for the prediction of the impact of small structural variations on self-assembly using paraxanthine. The computational results were supported by isothermal titration calorimetry experiments. The thermodynamic parameters enabled the quantification of the actual percentage of dimer present in solution as a function of concentration. The data suggest that both caffeine and paraxanthine are present at concentrations comparable to the ones found in biological samples.
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Affiliation(s)
- Luca Redivo
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
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Redivo L, Stredanský M, De Angelis E, Navarini L, Resmini M, Švorc Ĺ. Bare carbon electrodes as simple and efficient sensors for the quantification of caffeine in commercial beverages. ROYAL SOCIETY OPEN SCIENCE 2018; 5:172146. [PMID: 29892400 PMCID: PMC5990824 DOI: 10.1098/rsos.172146] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 03/27/2018] [Indexed: 06/08/2023]
Abstract
Food quality control is a mandatory task in the food industry and relies on the availability of simple, cost-effective and stable sensing platforms. In the present work, the applicability of bare glassy carbon electrodes for routine analysis of food samples was evaluated as a valid alternative to chromatographic techniques, using caffeine as test analyte. A number of experimental parameters were optimized and a differential pulse voltammetry was applied for quantification experiments. The detection limit was found to be 2 × 10-5 M (3σ criterion) and repeatability was evaluated by the relative standard deviation of 4.5%. The influence of sugars, and compounds structurally related to caffeine on the current response of caffeine was evaluated and found to have no significant influence on the electrode performance. The suitability of bare carbon electrodes for routine analysis was successfully demonstrated by quantifying caffeine content in seven commercially available drinks and the results were validated using a standard ultra-high performance liquid chromatography method. This work demonstrates that bare glassy carbon electrodes are a simple, reliable and cost-effective platform for rapid analysis of targets such as caffeine in commercial products and they represent therefore a competitive alternative to the existing analytical methodologies for routine food analysis.
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Affiliation(s)
- Luca Redivo
- Department of Chemistry and Biochemistry, School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | | | | | | | - Marina Resmini
- Department of Chemistry and Biochemistry, School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Ĺubomír Švorc
- Institute of Analytical Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského 9, Bratislava 812 37, Slovak Republic
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Schievano E, Tonoli M, Rastrelli F. NMR Quantification of Carbohydrates in Complex Mixtures. A Challenge on Honey. Anal Chem 2017; 89:13405-13414. [DOI: 10.1021/acs.analchem.7b03656] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Elisabetta Schievano
- Dipartimento di Scienze Chimiche, University of Padova, via Marzolo 1, 35131 Padova, Italy
| | - Marco Tonoli
- Dipartimento di Scienze Chimiche, University of Padova, via Marzolo 1, 35131 Padova, Italy
| | - Federico Rastrelli
- Dipartimento di Scienze Chimiche, University of Padova, via Marzolo 1, 35131 Padova, Italy
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Shi X, Zhang G, Mackie B, Yang S, Wang J, Shan L. Comparison of the in vitro metabolism of psoralidin among different species and characterization of its inhibitory effect against UDP- glucuronosyltransferase (UGT) or cytochrome p450 (CYP450) enzymes. J Chromatogr B Analyt Technol Biomed Life Sci 2016; 1029-1030:145-156. [DOI: 10.1016/j.jchromb.2016.06.031] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 06/17/2016] [Accepted: 06/18/2016] [Indexed: 10/21/2022]
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